Rotary fluid pump or motor

ABSTRACT

A gear pump is disclosed in which pressure plates engage and provide a dynamic seal with the ends of the gear elements. The side of each pressure plate remote from the gear is divided into two separate pressure balancing zones, one of which is maintained substantially at inlet pressure and the other at outlet pressure. A simplified seal assembly functions to seal the main housing and end caps and also to separate the two pressure zones. The main seal is ring-shaped and is formed with integral inwardly extending projections. The structure is arranged so that this seal can only be installed in the proper position. A second Ishaped seal separates the two pressure zones at a location between the bearings. Here again, such seal can be installed only in a single proper installed position. Both seals are pressure actuated to insure proper and complete sealing.

United States Patent 1 91 Wellman [4 Dec. 11, 1973 1 ROTARY FLUID PUMP 0R MOTOR Primary Examiner-Carlton R. Croyle Assistant Examiner-John J. Vrablik 75 l *t:EllM.Wll h I l or Is 8 P C ardon Ohm Att0mey-Harold F. McNenny et al. 173i Assignee: The Weatherhead Company, '1

Cleveland, Ohio L d I ZT ETh l gear pump is 186 ose m w 1c pressure p ates en- [22] 1972 gage and provide a dynamic seal with the ends of the [2]] A N 222,909 gear elements. The side of each pressure plate remote from the gear is divided into two separate pressure balancing zones, one of which is maintained substan- [52] US. Cl. 418/132 tially at inlet pressure and the other at outlet pressure [511 3" 19/08 F03C 3/00 F04c 15/00 A simplified seal assembly functions to seal the main 158] Field of Search 418/131, 132, 133 housing and end caps and also to separate the two pressure zones. The main seal is ring-shaped and is [56] em-mus C'ted formed with integral inwardly extending projections. UNITED STATES PATENTS The structure is arranged so that this seal can only be 3,482,524 12/1969 413/132 installed in the proper position. A second I-shaped 3,348,492 10/1967 418/131 seal separates the two pressure zones at a location be- ,887 5/1971 418/132 tween the bearings. Here again, such seal can be installed only in a single proper installed position. Both 3:499:390 3/1970 418/132 seals are pressure actuated to insure proper and complete sealing. I

7 Claims, 3 Drawing; Figures PATENTED 7 3.778.200

SHEET 2 BF 2 it ROTARYE FLUID PUMP OR MOTOR BACKGROUND OF THE INVENTION This invention relates generally to rotary fluid pumps and motors having pressure balanced end plates and more particularly to such devices incorporating novel and improved seal structures.

PRIOR ART Various types of prior art rotary fluid pumps and motors are provided with pressure balanced end" plates which engage and seal with the ends of the rotor. The intention in suchdevices is to provide a force of engagement between the pressure plate and the ends of the rotor which is automatically adjusted for variations in the pressure conditions'within the pump or motor. In

some instances, the structure is arranged so that the rearward surface of the pressure plates is divided into two'or more zones which are maintained at different pressures which are related to the pressure condition within the pump.-The U.S. letters Pat. Nos. 2,756,681;

2;866,4l6; and 3,011,448 disclose pumps of this general type.

SUMMARYOF THE INVENTION In accordance w ith the present invention, a structure isprovided in which a novel and improved seal structure is utilized to divide the balancing chamber on the rearward side of the pressure plate into at least two separated zones-which can be separately maintained at different pressuresre'lated to the pressure conditions existing in the device. r

The illustrated embodiment of this invention is a gear pump having two intermeshing gears contained within a pump chamber "in a housing assembly. The housing ing and the associated end caps to provide a seal therebetween and isiprovidedwith two inwardly extending integral projectionswhich extend in along the rearward surface of theassociated pressure plate to the outer race of the. bearing :in order to divide the balancing chamber into two -separate pressure zones which are maintained at different pressures. In addition, a sepageneral structural arrangement of a pump incorporating this invention; 1

FIG. 2 is an end view with one end cap removed illustrating the position of the seals and the structure for mounting the seals; and

FIG. 3 is an exploded perspective view illustrating the main housing, one pressure plate and two seal elements associated therewith.

DETAILED DESCRIPTION OF THE DRAWINGS The present invention is illustrated as applied to a rotary gear pump. It should be understood, however, that the invention is equally applicable to motors. The illustrated pump is provided with a housing assembly 10 consisting of a main housing member 11 and two end caps 12 and 13. The main housing member 11 is formed with a pump chamber 14 (having a shape as best illustrated in FIG. 3) which includes side lobes 16 and 17 proportioned to receive associated intermeshing gear pump members 18 and 19, respectively. Formed along the upper side of the pump chamb'er 14 is an outlet section 21 and an inlet section 22 is formed along the lower portion. The outlet portion 21 communicates at its end with an outlet passage system formed in the end cap 12 (not illustrated), and the inlet portion 22 communicates with an inlet passage system 23 in the end'cap 12.

The two gear pump members 18 and 19 are journaled in roller bearings 24 at each end, each of which includes an outer race 26 pressfitted into the associated end cap 12 or 13. Each gear pump member 18 and 19 is provided with an extension 27 extending through the end cap 12 so that the pump may be connected to be driven by any suitable drive system.

A pair of similar pressure plates 28 and 29 are positioned within the housing assembly to engage the opposite ends of the gear portions of the gear members 18 and 19 to form a dynamic face seal therewith. The force of engagement of the pressure plates against the gear members is controlled automatically by the fluid pressure existing along the rearward face thereof within a control chamber 3ldefined by each plate and its associated end cap in the zone radially outward from the associated outer races 26 of the bearings 24.

In order to provide proper balancing of thepressure plates so that the portions thereof adjacent to'the inlet or low pressure side of the pump are not excessive and so that the portions thereof adjacent to the outlet or rate seal insert is located in the zone between the bearings to prevent communications between the two pressure zones inthis area. In the illustrated embodiment both seals are pressure actuated to insure tight sealing engagement with the bearing to prevent leakage.

With the illustrated structure, proper and easy installation of the two" seals at each end of the pump is assured, and it is not necessary to install a large number of smallseal elements which individually can be improperlypositioned to cause undesired leakage. With the structure in accordance with the present invention, the cost of manufacture isreduced and proper assembly is achieved w itha minimum of labor and with a high pressure portion of the pump are not too small, the control chambers are separated into at least two pressure control zones by a pair of seals 32 and 33. The

zones are sized and located so that a proper balancing force is developed on the rearward side of the pressure plate urging it toward engagement with the associated gear members. This balancing automatically adjusts to maintain the proper relationship to the pressures existing at any given time within the pumping chamber.

The seal 32 is shaped in its moldled condition as a ring 34 provided with two inwardly extending projections 36and 37 integrally formed therewith. The seal 33 is generally I-shaped and providestwo end portions 38 and 39 connected by a central web 41. It should be understood that a seal 32 and associated seal 33 are provided at each end of the pump in association with each of the pressure plates 28 and 29. The ring portion 34 of each seal 32 is positioned within a groove '42 formed in the-face of the main housing 11 which extends completely around the pump chamber 14 and is engaged by the associated end cap 12 or 13 to provide a complete seal between the main housing 11 and associated end 12 or 13.

The main housing is also provided with a generally radially extending pair of grooves 43 and 44 which extend from the groove 42 toward the adjacent section of the pump chamber 14. When the pressure plates are installed within the main housing, the grooves 43 and 44 are in alignment with a pair of grooves 46 and 47, respectively. The various elements are proportioned so that the seal projections 36 and 37 extend along the respective grooves 43 and 44 in the housing and the grooves 46 and 47 in the associated pressure plates into abutment with the adjacent outer race 26 of the bearings as best illustrated in FIG. 2.

The pressure plates are formed with additional grooves 48 and 49 so that the pressure plates are symmetrical and can be assembled in the main housing in either of two positions. This eliminates the need of selective assembly and reduces the possibility of improper assembly of the pump.

The seal 33 is positioned within a mating groove 51 formed in the central portion of the rearward face of the pressure plates and the various elements are proportioned so that the portions 38 and 39 extend into engagement with the adjacent outer races of the bearmgs.

The pressure plates are formed with shallow bores 52 which closely fit the outer races 26 and are formed with an outer periphery 53 which closely fits the wall of the pump chamber along the two portions 16 and 17 to limit circumferential leakage. The two seals 32 and 33 effectively function to divide the control chamber 31 into a first zone 54 in communication with the outlet portion 21 and extending from the seal projection 36 to the seal projection 37. The second zone 56 which is in communication with the inlet portion 22 is isolated from the first zone 54'by the projections 36 and 37 in cooperation with the seal 33. The second zone 56 is maintained at substantially inlet pressure and the first zone 54 is maintained at a pressure substantially equal to the outlet or output pressure of the pump. The two pressure zones 54 and 56 are sized andpositioned so that they automatically function to produce the required amount of force on the rearward side of the pressure plate to maintain proper sealing engagement between the forward side of the pressure plate and the adjacent end of the gear members.

In the illustrated embodiment both of the seals are pressure actuated. The grooves 43 and 46 and the grooves 44 and 47 are oriented so that the two projections 36 and 37 respectively project in a direction in which an extension of each would pass on the outside of the axes of the associated bearings. Consequently, the higher pressure in the zone 54 tends to move the projections toward the low pressure zone 56 and causes the projections to move toward a position where the radial spacing between the associated outer bearing race from the root of the projection is less. This movement causes an increase in the pressure of engagement between the ends of the projections and the associated outer bearing race 26 and prevents leakage therebetween.

A similar arrangement is provided with respect to the seal 33. The end portion 38 of the seal is located above a line connecting the bearing axes. Therefore, the

higher pressure in the zone 54 tends to push the upper portion 38 down between the converging surfaces of the bearing races 26 and increases the endwise pressure between the portion 36 and the two races 26. The associated grooves are proportioned to allow sufficient movement of the seals to insure this pressure actuation of the seals.

Each of the gear members 18 and 19 is provided with a central bore 57 open through a radial passage 58 to the zone of the interior of the adjacent bearing 24 within the end cap 12 and the portion thereof outboard of such bearings. A pair of diagonal passages 59 connect the ends of the bearing sections in the cap 13 to the inlet port 23. Such passages insure that the interior of the bearings are maintained at the inlet pressure. With this structure, a seal 61 provided for each gear member is not subjected to any substantial pressure, and leakage from the pump is virtually non-existant.

With the illustrated structure, the assembly of the pump is greatly simplified since it is only necessary to position four seal elements with two at each end of the pump. The seal 32 performs the combined function of completely sealing the interface between the main housing and the associated end cap and, in addition, providing a portion of the scaling function of separating the two control zones 54 and 56. Similarly, the single seal element 33 positioned in the pressure plate completes the zone separating function. It is virtually impossible to place the seal 32 in the assembly in an incorrect position because the seal can only be received within the grooves 42, 43 and 44 in the proper position and when so positioned, also extends along the proper grooves within the pressure plate. Similarly, the exact proper positioning of the seals 33 is insured due to the Hype structure in which each of the lateral portions 38 and 39 are positioned with respect to the corresponding grooves by the web section 41. It will be recognized that with the structure, the skill and care required of the assembler is greatly reduced and reliable assembly is greatly improved.

Although a preferred'embodiinent of this invention is illustrated, it should be understood that various moditications and rearrangements of parts may be resorted to without departing from the scope of the invention disclosed and claimed herein.

I claim:

l. A rotary pump, motor or the like comprising a housing assembly providing an inlet and an outlet, said housing assembly including a main housing providing a main chamber in communication with said inlet and outlet at spaced locations and an end cap closing each end of said main chamber, first and second similar rotary gears provided in said main chamber meshing together, a pressure plate and a seal assembly provided at each end of said gears engaging and sealing with the adjacent ends of said gears, the rearward side of each pressure plate remote from said gears cooperating with said housing assembly to define a control chamber in communication with said inlet and outlet, bearings for said rotary elements providing non-rotating axially ex tending surfaces located in each of said control chambers, a unitary seal member providing a seal between said housing and each of said end caps around said main chamber, said seal members including integral projections extending along the rearward sides of the associated pressure plate into engagement with the surface of the associated bearing, a second seal provided in each control chamber engaging the surfaces of the associated bearings, said seals and bearing surfaces separating each control chamber into a first pressure zone in communication with said inlet and a second pressure zone in communication with said outlet, said housing assemblyproviding first non-symmetrical seal retaining grooves proportioned to receive said unitary seals only in a correct installed position, second symmetrical grooves being provided for said second seal members claim 3 wherein said second grooves are located in said pressure plate.

5. A rotary pump, motor or the like as set forth in claim 1 wherein said gears are journaled in anti-friction bearings each having an outer bearing race, and said seals each extend into engagement with the associated outer bearing races.

6. A rotary pump, motor or the like as set forth in claim 5 wherein the pressure in two pressure zones tends to move at least said integral projections toward positions of increased pressure of engagement with the associated outer races.

7. A rotary pump, motor or the like as set forthin claim 5 wherein the pressure in the two pressure zones tends to move said seals toward positions of increased pressure of engagement with the associated outer races. 

1. A rotary pump, motor or the like comprising a housing assembly providing an inlet and an outlet, said housing assembly including a main housing providing a main chamber in communication with said inlet and outlet at spaced locations and an end cap closing each end of said main chamber, first and second similar rotary gears provided in said main chamber meshing together, a pressure plate and a seal assembly provided at each end of said gears engaging and sealing with the adjacent ends of said gears, the rearward side of each pressure plate remote from said gears cooperating with said housing assembly to define a control chamber in communication with said inlet and outlet, bearings for said rotary elements providing non-rotating axially extending surfaces located in each of said control chambers, a unitary seal member providing a seal between said housing and each of said end caps around said main chamber, said seal members including integral projections extending along the rearward sides of the associated pressure plate into engagement with the surface of the associated bearing, a second seal provided in each control chamber engaging the surfaces of the associated bearings, said seals and bearing surfaces separating each control chamber into a first pressure zone in communication with said inlet and a second pressure zone in communication with said outlet, said housing assembly providing first non-symmetrical seal retaining grooves proportioned to receive said unitary seals only in a correct installed position, second symmetrical grooves being provided for said second seal members proportioned to receive said second seal members only in a correct installed position.
 2. A rotary pump, motor or the like as set forth in claim 1, wherein said seal member includes a ring-shaped portion and a plurality of inwardly extending projections.
 3. A rotary pump, motor or the like as set forth in claim 1 wherein said second seal member and said second grooves are I-shaped.
 4. A rotary pump, motor or the like as set forth in claim 3 wherein said second grooves are located in said pressure plate.
 5. A rotary pump, motor or the like as set forth in claim 1 wherein said gears are journaled in anti-friction bearings eaCh having an outer bearing race, and said seals each extend into engagement with the associated outer bearing races.
 6. A rotary pump, motor or the like as set forth in claim 5 wherein the pressure in two pressure zones tends to move at least said integral projections toward positions of increased pressure of engagement with the associated outer races.
 7. A rotary pump, motor or the like as set forth in claim 5 wherein the pressure in the two pressure zones tends to move said seals toward positions of increased pressure of engagement with the associated outer races. 